I am paying to support my husband’s drunken ex

Can someone please tell me how the hell the CSA get away with not only fleecing my partner for near on his whole wages that are hard earnt and then have the bloody cheek to decide to take extra money after assesing my wages despite having a dependant of my own that resides with us and i support single handed?

This is after his lazy blood sucking ex appealed the reduction of the first assesment. It took the CSA 9 months to sort it out and no contact between the CSA or us notifying us of her appeal until a massive £587.64 was deducted from his pay packet ! Jesus what a shock and right on x-mas! I have appealed it and lost and was basically told that it was arrears and standard payments and that it has to be paid!

Where is the justice for those of us who have never had an issue paying to support our kids yet get stiffed for doing so!! An extremely fed up VICTIM!!